Inflatable containers such as balloons can be filled with a variety of fluids, such as air, helium, water, medicines, etc. In some cases, a lot of inflatable containers may need to be filled with fluids. For example, balloons used as props in conventions, large parties, etc. may number in the hundreds and may require substantial human effort to fill them all in a timely manner. In another example, water balloons used as kids' toys may need to be filled in large numbers to aid in various games. Various methods may be employed to fill such inflatable containers. For example, an individual may blow up and tie each balloon by hand or use a tank of compressed air or helium to inflate the balloon, which then has to be tied. In another example, an individual may fill water balloons with water by hand one at a time, and then tie the balloons, which can all be quite time-consuming. Moreover, the inflatable containers may be damaged or filled to different volumes. Various containers are particularly suitable for containing liquids, yet may be subject to undesirable leaks that may allow liquid to escape the container.